Firing mechanism for firearms



Dec. 5, 1961 H. H. sEFRn-:D n 3,011,282

FIRING MECHANISM FOR FIREARMS v Filed Jan. 19, 1959 INVENTOR HARRY H.SEFRIED 1I bis Arran/5v5.

@wird v;.

dl LZSZ Patented Dec. 5, i961 3,011,282 FG MECHANISM FOR FEES Harry H.Sefried lll, New Haven, Conn., assignor to The High StandardManufacturing Corporation, Harnden, Conn., a corporation of ConnecticutFiled lan. i9, 1959, Ser. No. 787,489 d Claims. (Cl. t2-69) Thisinvention relates to improvements in tiring mechanisms for firearms, andit relates more particularly to sear means which will provide a crisptrigger and at the same time prevent accidental discharge of thefirearm.

ln target shooting, it is extremely important to reduce r to eliminate,if possible, anything which distracts the marksman from keeping hissights on the target at the instant he lires the gun. One of the thingswhich is most distracting to an expert marksman in firing a gun is anoticeable movement of the trigger, known as trigger creep, which hefeels as he squeezes the trigger. Such movement is particularlynoticeable if the trigger pull is light. A trigger mechanism having alight trigger pull and a very slight amount of movement of the triggerbcfore the let-off point, at which the tiring member is released, is ahighly desirable feature in a target gun. 'It is difficult, however, toprovide a crisp trigger and a light trigger pull together.

Heretofore only guns which have been extremely accurately made byadhering to close tolerances have had both a light trigger pull and acrisp trigger. 'Such guns, however, must be virtually hand-made and aretherefore too expensive for the Vast majority of people who would liketo have a target gun with the characteristics required for that type ofshooting. Moreover, even in the most carefully manufactured firearm alarge degree of safety is usually sacrificed in order to obtain a lighttrigger pull and the desired crispness in the trigger. This is due tothe fact that any shock or jar may cause fall-off of the sear releasingthe hammer or other tiring member' that may be employed. Target shootingguns have, therefore, been somewhat more dangerous to handle than othertypes of firearms.

lt is accordingly an object of the present invention to provide a tiringmechanism with a crisp trigger action, which can be manufactured on aproduction basis and which will be safe under conditions generallyreferred to as traumatic. A speciiie object of the invention is toprovide a sear which has substantially greater actual sear travel thanis normally provided in order to greatly reduce, if not actually do awaywith, the danger of accidental firing, while at the same timeeliminating trigger creep. Another object of the invention is to provideimproved sear engagement permitting a light trigger pull as well as acrisp trigger, without detracting from the safety of the gun.

These and other objects of the invention, as well as its novel featuresand advantages, will become further apparent from the descriptionhereinafter.

in general the invention contemplates provision of interengagingportions of the ring member and sear whereby the initial movement of theSear out of its cocking engagement with the tiring member requires -afairly light, but more or less normal, trigger pull; but wherein after aminimum amount of travel of the scar, the angle of the surface, againstwhich the force tending to operate said tiring member is exerted, ischanged relative to such force so as to substantially reduce the amountof trigger pull required to release the firing member. -In its mostadvantageous form, the invention includes the provision of a safetysurface on the sear which is disposed at an angle to the latchingsurface thereof, the latching surface being normally engaged by acooking-abutment on the hammer or other firing member when the sear isin its full-cooking position, said safety surface being located so thatit will be engaged by the cooking-abutment upon movement of the searfrom its full-cocking position. The angle which the safety surface makeswith respect to the latching surface and the angle which said surfacemakes with respect to the force exerted on it by said cookingabutment,are such that ir the sear is jarred from its fullcocking position sothat the cooking-abutment contacts the Safety surface instead of thelatching surface of the scar, the spring means urging the Sear intoengagement with the firing member will return the sear to itsfull-cooking position with the tiring member. On the other hand, whenthe sear is moved out of cooking position in the usual manner by meansof the trigger, the force required to overcome the resistance of thetrigger while the cocking-abutment engages the latching surface is somuch greater than the force required to move it once thecocking-abutment contacts the safety surface that the safety surface ofthe Sear will be moved on past the cooking-abutment due to inertia ofthevshooters trigger finger alone. In other words, even if the shooterwanted to release the trigger' at the instant the cooking-abutmentpasses the apex of the angle between the latching surface and the safetysurface, he could not do so.

One particularly desirable embodiment of the invention is illustrated inVthe accompanying drawings, in which FG. l is a side elevational view,partly broken away and partly in cross-section, of a pistonincorporating the invention;

FIG. 2 is an enlarged perspective View of the hammer and sear; and

FIG. 3 is a diagrammatic view of the interengaging portions of thehammer and scar within the area defined by the circle in FlG. 2 andshown on a greatly enlarged scale, the hammer and sear being shown linedas if in cross-section.

The tiring mechanism of the semi-automatic pistol of the so-calledblow-back type shown in the drawings for illustrative purposes consistsof a tiring pin 10 longitudinally movable in a slide l2 whichreciprocates longitudinally on the frame i4 in a well known manner.Firing pin lll is urged rearwardly by a spring ll so that its rear endnormally projects slightly rearward o-f a vertical wall 16 inside slidei2 in position where it can be struck by a pivoted hammer 1S in order tore a cartridge (not shown) positioned within the chamber of a barrel 20mounted forwardly of slide l2 and against which slide 12 is forced by areturn spring (also not shown).

Hammer lit` is pivoted on a pin 2,2 supported at both K ends in frame i4and is operated by a hammer spring 24 located in the grip portion offrame 1d on a hammer strut 2d which at its upper end is pressed by meansof spring 24 against a pin 2S mounted in hammer 18 in a more or lessconventional manner.

vided in the under edge of hammer 18 and through which pin 28 extends. Asear 3.2 is pivoted Vrearwardly of hammer 1S on a pin 3d supported inframe 14. The sear nose 36 of sear 32 extends downwardly and slightlyforwardly into a sear notch 38 in the cylindrically shaped rear edge 39of hammer 18 with the forward tip 40 of scar SZAlatching with thecooking-abutment on the hammer at the lower corner 42 of scar notch 3rd(see FIG. 2). It will be noted that in accordance with usual practice,the direction of the force exerted by hammer spring 24 on hammer 1S whenthe latter is cocked, is only slightly to one side of pivot pin 22.Consequently, a relatively small force is exerted by sear notch corner42 on sear 32 thereby reducing the tendency for these members to bind,which would result in an extremely poor trigger action. Moreover, whenthe hammer falls to the broken line position shown in PEG. l, the fullforce of hammer The upper end ofV hammer strut 26 lits into a deep slot30 (FlG. 2) prospring 24 is applied as the hammer strikes the tiring pin10.

The sear nose 36 of sear 32 is urged forwardly by a sear spring 44 intoengagement with the rear edge 39 of hammer 1S so that the front edge ofsear nose 36 engages the hammer adjacent the upper corner of sear notch3S and the tip 4G of sear 32 projects slightly into sear notch '38 intothe path of the lower corner 42 thereof. Accordingly, when the hammer ispivoted back (clockwise as shown) somewhat beyond its full-line positionas seen in FIG. l during the rearward stroke of slide 12, the nose 4l)of sear 32 will project into sear notch 33 and, on the forward stroke ofslide 12, the sear notch corner 42 engages the under edge or searsurface of sear nose itl so that further movement of the hammer isarrested.

A. sear bar 46 extending longitudinally of the frame and actuallylocated outside of the side wall of frame 14, which has been removed inFG. 1 in order to show the firing mechanism, is illustrated in itsrelative position with respect to the other parts of the gun. Sear bar46 connects the trigger 48 with the upper end of sear 32 so that whenthe trigger is pulled, sear 32 will be rotated counterclockwise as shownin FIG. l in order to release hammer 1S and lire the gun. To this end,sear bar 46 is pivoted at its forward end to the upper end of trigger4S, which in turn is pivoted about the trigger pivot pin Sil. Adjacentits opposite or rear end, sear bar 46 is provided with an upwardlyfacing notch 52 which receives a lug 54 on the upper end of sear 32. Asearbar spring (not shown) exerts an upwardly and rearwardly directedforce against the front side of a finger portion 56 on the under side ofsear bar d6 in order to resiliently urge notch 52 into engagement withlug 54 on sear 32, while at the same time to urge sear bar 46longitudinally to the rear. The rearward component of this action willpivot trigger d8 in a clockwise direction as viewed in FIG. l in orderto return trigger 48 to its normal position, or to maintain it in thatposition whenever sear bar 46 is disconnected from sear 32.

Provision for disconnecting the sear from the trigger is of courseessential in a semi-automatic firearm of the type here shown in orderthat the gun will not fire in machine gun fashion if the trigger is heldin its retracted position. For this purpose, a hump 53 is provided onthe upper edge of sear bar 46 which is depressed by the slide 12immediately after a cartridge is fired, thereby dropping the notch S2out of engagement with lug 54 on sear 32 so that the sear can swing backunder the urge of sear spring 44 into position for engagement with searnotch 38 as soon as the hammer is returned to cocked position. Sear bar46 is positively prevented from lifting into engagement with sear lug 54until slide 12 returns to battery position and the trigger 48 isreleased so that the sear bar can move longitudinally rearward under theurge of the aforesaid sear-bar spring.

A sear spring adjusting device shown generally at 60 is provided in therear of frame 14, but since this forms no part of the present invention,it is not described in detail here. In addition, the usual safety notch61 is provided in case the sear should not engage properly with searnotch 38 or should become accidentally disengaged therefrom.

Referring now more particularly to FIG. 3, the portions of sear 32 andhammer 18 there shown on a greatly enlarged scale are lined as if incross-section for purposes of clarity. It will be apparent from FIG. 3that only the sear notch corner 42, sometimes referred to herein as thecooking-abutment of the firing member, engages the under edge of the tip4G of sear 32 and, therefore, in this instance only a line Contact ismade between the cooking-abutment and sear 32. In other words, there isno surface-to-surface contact between the sear notch 38 and the searnose 36. Consequently, all the force exerted by the hammer 18 bearsalong this line of contact. The arrow F in FIG. 3, which isperpendicular to a line through the pivot point of the hammer and thecorner 42, represents the force exerted by hammer 18 on sear 32.

The primary feature of the present invention comprises the provision ofa safety surface 62 on the sear surface of sear 32. Such safety surfacein the specific example illustrated in the drawings is formed betweenthe point B, commonly known as the fall-off point, at the front edge ofthe sear and the point A, which is the apex of an angle formed betweenthe safety surface 62 and the larching surface 64 rearwardly of point A.Point B in the present arrangement is the point at which the hammer isactually released by the seat', and the latching surface 62 is thatsurface with which the cocking-abutment or sear notch corner engages tolock the hammer 'when the sear is in its full-cocking position. Latchingsurface 64 is disposed with respect to the direction of the force Fexerted by the hammer on the sear at any angle X which may be desirablefor the purpose of adequately retaining the sear in engagement with thesear notch corner 42, while at the same time providing the desiredtrigger pull when the trigger 43 is actuated.

The safety surface 62 is disposed at an angle Y on the order `of 10 to20 with respect to the plane of latching surface 64. When the sear ismoved out of its full-cooking position, in which it is shown in fulllines in FIG. 3, to bring safety surface 62 into Contact with the searnotch corner 42, as indicated in dash-dot lines, safety surface 62 formsan angle Z with respect to the direction of cooking-abutment force F.Angle Z may vary considerably depending on several factors, includingthe magnitudes of the forces exerted by sear spring 44 and the sear bar46, which urge sear 32 into engagement with hammer 187 as well as thedesired angle of engagement of latching surface 64. The generalprinciple, however, which determines the angle at which safety surface52 should be disposed to the force exerted on it by the cooking corner42 is, as has been mentioned hereinbefore, that whenever under staticconditions the corner 42 engages safety surface 62, the sear 32 will bemoved by the forces exerted on it into its full-cooking position, andfurther that whenever the trigger is manipulated so as to move sear 32from its full-cooking position to a point where the corner 42 engagessafety surface 62, the reduction in the force required to move sear 32,as the corner 42 passes the apex point A, will be so great that therewill be no apparent further resistance to the pull of the trigger,rendering it impossible at this point for the shooter to voluntarilyprevent the gun from firing.

t will be seen yfrom the foregoing that provision of the safety surface62 has the elfect of providing a sear travel which is many times thatordinarily used in sear devices of this type, while making only a verysmall amount of such travel effective in perceptibly resisting actuationof the trigger. Thus, the chances of the sear being jarred olf thecocking-corner of the hammer are greatly reduced, if not entirelyeliminated, by the safety surface of the present invention. At the sametime, since the relative movement between the sear and cockingcorner cannot be detected by the shooter when the cocking-corner engages thesafety surface, there is no movement of the sear which is perceptible tothe shooter because the amount that the sear must move while thecocking-corner is in contact with the latching surface behind the apexof the safety angle is so small that it can not be felt.

In order to illustrate the principles of the invention still further, anexample will be given of specific angles and dimensions withinmanufacturing tolerances of the latching and safety surfaces which havebeen found to provide highly satisfactory results in the type of ringmechanism hereinbefore specifically described. Thus, the

latching surface 64 may be disposed at an angle to the direction of theforce F such that angle X is equal to approximately 83, while the angleY between safety surface 62 and the plane of latching surface 64 isequal to about making the angle Z between safety surface 62 and force Fin the vicinity of 87. It should be noted here that due to rotationalmovement of sear 32 in this particular type of tiring mechanism, theangle of safety surface 62 to force F changes slightly whencockingcorner l2 engages surface 62. Such change, however, is always ina direction which will reduce the tendency for the cooking-corner toslip off the sear. When the scar is in its full-cooking position, asshown in full lines in FIG. 3, the effective sear travel, so-called, ordistance from the cooking-corner 42 to the apex A of the safety angle isfrom 0.003 to 0.004 'of an inch. The distance from the apex A to therelease point B along safety surface 62 is in this instance a maximum of0.009 of an inch. The over-all Sear travel is, therefore, approximatelytwelve or thirteen thousandths of an inch, While the effective seartravel insofar as the action of the trigger is concerned is only aboutone fourth of the total Sear travel.

In this connection, it is of interest to note that a gun in which thesear travel is two or three thousandths of an inch is considered to bedangerous, even though it may be manufactured with the greatest care andbe provided with the usual safety devices, such as the safety notch onthe hammer. Ordinarily, however, at least four to six thousandths of aninch sear travel is provided. Consequently, the present inventionprovides even greater actual sear travel than is normally provided and,therefore, provides a gun which is even safer than most without theexpected trigger creep which has heretofore characterized gunsconsidered to be safe. A gun incorporating the hereinabove describedtiring mechanism, and having substantially the speciiic dimensions andangles of the scar engagement mentioned, has a trigger pull of only twopounds as compared to other guns which have a comparable degree ofsafety requiring at least three or four pounds trigger pull.

Although it has been mentioned hereinabove that the angie Y between thesafety surface 62 and the plane of latching surface 64 is equal to about10 or 20, it is believed to be practical to reduce this angle to onlyabout 5, if desired, or to make it as large as 30 or more. It will alsobe noted that in the specific example given above the force exerted bythe hammer on the sear is not exactly perpendicular to the safetysurface when the cooking corner of the hammer engages this surface. Thearrangement in this case is such that the force of the hammer actuallytends to urge the sear against the sear spring, which therefore lightensthe force required to retract the sear. On the other hand, the latchingsurface is so disposed that the hammer must be slightly depressedagainst the urge of the hammer spring so that a much greater force isrequired to retract the sear than is the case when the cooking cornercontacts the safety surface. It will be appreciated, however, that thesafety surface could be disposed perpendicular to the direction of theforce exerted by the hammer on it, if desired. Moreover, if the latchingsurface were disposed at a sharper angie X with respect to the cookingcorner, providing a relatively heavy trigger pull, the angle Z to thesafety surface might even be greater than 90 s0 long as the torquerequired to retract the sear at this point is substantially less thanthat required when the latching surface engages the cooking corner ofthe hammer.

in determining the length of the safety surface 62 or distance betweenthe points A and B in FIG. 3, the maximum amount of deviation of Sear 32from its fullcocking position should be determined under variousconditions of shock to which thegun may be subjected, as for example incase it is dropped. The safety surface may then be made to allow for theworst condition Vwhich may be expected, so that the Sear can not jumpbeyond the edge of the safety surface, but will come to rest momentarilywith the cooking-corner on the safety surface. It will be understood,however, that the cookingcorner does not remain in engagement with thesafety surface because, as has been brought out hereinabove, thatsurface is so arranged that the resultant of the forces acting on thesear under such conditions will cause it to return immediately to itsfull-cooking position.

The term static condition, as used herein in connection with theconditions wherein the cooking-abutment engages the safety surface,refers to the instant at which the sear comes to rest after it has beenjarred from latching-surface engagement by an external blow on the fgun.Such static condition may be likened to ya hypothetical situation inwhich the sear is physically' set in such a position that the safetysurface engages the cocking-abutment and then is released.

A further advantage of the invention which should be mentioned here isthat, due to the provision of the safety surface, the gun will notbecome unsafe in case the corner |42 of Sear notch 3S becomes vroundedoi slightly because of wear. Thus, so long as the point of engagement ofcorner 42 is behind the apex A of the safety angle, the hammer 18 cannot fall oif the sear accidentally. In conventional Sear engagements,however, if due to wear the point of engagement of the cooking-corner onthe hammer becomes as little as one or two thousandths of an inch fromthe release point on the sear, there will be serious danger ofaccidental firing of the gun. Moreover, by providing the safety surfaceof the present invention, the corner 4Z on the hammer can be purposelymade to engage the latching surface 64 within only one or twothousandths of yan inch of the apex A of the safetyangle without makingthe gun unsafe, thereby obtaining the advantage of a hair-trigger ineliminating creep.

While the hereinabove-described example of one particularly desirableembodiment of the invention contemplates provision of the so-calledsafetyand latching surfacesV as being located on the sear, it will beunderstood that one or both of said surfaces could be formed on thefiring member instead of on the sear. Such modications therefore comewithin the scope of the present invention as defined by the appendedclaims.

What is claimed is:

l. In a tiring mechanism having a ring member, a sear member movableinto and out of cooking engagement with said firing member, a spring foroperating said tiring member, lspring-means for resiliently uring saidSear member into engagement with said tiring member, and trigger meansfor positively moving said sear member against the resilient force ofsaid spring-means out of said cooking engagement; the improvement in theinterengagement of said sear member with said tiring member comprising alatching surface on one of said members engageable with a portion of theother of said members when said Sear is in its full-cooking position,said latching surface forming an angle with the direction of the forceexerted on said Sear member by said tiring member which requires asubstantially normal trigger pull in order to move said sear member outof said fullcocking position, and a safety surface on one of saidmembers disposed at an angle` with said latching surface and located soas to be engaged by a portion of the other of said members upon movementof said sear member a predetermined distance from said full-cockingposition, said safety and latching surfaces being substantially ilat anddisposed so that said firing member is held in cocked position byengagement of either of said surfaces, said safety surface forming anangle with respect to the direction of said force on said sear membersuch that thertrigger pull required to move said -sear member out ofsaid cooking engagement when said safety surface is 7 engaged by theother member is negligible compared to said normal trigger pull.

2. In a ring mechanism, a tiring member having a cooking-abutment, asear movable into and out of engagement with said cooking-abutment, aspring for operating said ring member, spring-means for resilientlyurging said Sear into engagement with said firing member, and `triggermeans for positively moving said sear out of engagement with saidcooking-abutment against the resilient force of said spring-means; theimprovement comprising a latching surface on said sear engageable withsaid cooking-abutment When said lsear is in its fullcocking position,and a safety surface on said sear located between said latching surfaceand the actual release point on said Sear, said latching and safetysurfaces each being substantially at and disposed at an angle to thedirection of the force exerted by said cocking-abutment on said searsuch that said spring-means will move said sear into said fu'll-cockingposition whenever under static conditions said cooking-abutment engagesSaid scar at any location between said full-cocking position and saidactual release point; said safety surface being disposed at a differentangie to the direction of said force exerted by said cooking-abutmentfrom that of said latcliing surface, said surfaces being contiguous andforming an abrupt angle at their intersection such that, whenever saidtrigger means is manipulated so as to move said sear from saidfull-cooking position bringing said safety surface into engagement withsaid cocliing-abutmen-t, said spring-means is incapable of preventingrelease of said tiring member.

3. In a tiring mechanism, a firing member having a cooking-abutment, asear movable into and out of engagement with said cocking-abutment, aspring for operating said ring member, spring-means for resilientlyurging said sear into engagement with said cookingabutment and triggermeans for positively moving said sear out of engagement with said firingmember against the resilient force of said spring-means; 'theimprovement comprising a latchirrg surface on said sear engageable withsaid cocking-abutment when said sear is in its fullcocking position anda safety surface on said sear contiguous with and forming an abruptangle with said latching surface, said safety surface being located soas to be engaged by said cocking-abutment upon movement of said searfrom its full-cocking position, said safety and latching surfaces beingsubstantially flat and disposed so that said ring member is held incocked position by engagement of either of said surfaces, said safetysurface being disposed rellative to said cooking-abutment such that thetrigger pull required to move said Sear when said cookingabutmentengages said safety surface is substantially less than the trigger pullrequired to move said Sear when said cooking-abutment engages saidlatching surface.

4. In a ring mechanism, the impro-vement deiined in claim 3, wherein theangle between said safety surface and the plane of said latchingsurfaces is equal to from 10 to 20.

References Cited in the file of this patent UNITED STATES PATENTS402,423 Ehbets Apr. 30, 1889 2,143,028 Pike Ian. 10, 1939 2,331,405Loomis Oct. 12, 1943 2,462,585 Wesson Feb. 22, 1949 2,775,836 EmersonJan. 1, 1957

